Mechanical recording of oscillations



Patented Dec. 8, .1936

MECHANICAL RECORDING OF OSCILLATIONS Willem Six, Elndhoven, Netherlands, assignor to hoven, Netherlands Philips 'Gloeilampenfabrieken, Eind- Application June 29, 1935, Serial No. 29,15 In. Germany July 19,- 1934 15 Claims.

My invention relates to a device for use in the mechanical recording of oscillations on a carrier, and more .particularly in the mechanical recording of sound oscillations.

The invention is particularly adapted for use in methods of mechanical recording in which a recording member is vibrated either perpendicularly to the surface of the carrier or is illbrated in a direction having a component permethods of mechanical recording have been described in the U. S. Patent No. 1,919,116 to James A.Miller, and I shall describe my invention in connection therewith; however its .useis not limited thereto.

I have found that in such mechanical re- When mechanically recording vibrations upon a carrier of nonuniform thickness, the track cut with the cutter, in its central or neutral position, i. e., when'the cutter is not vibrated, is not of constant width, but has a varying width due to the variations in thickness ,of the carrier.

When the cutter is vibrated in accordance with p the vibrations to be. recorded the boundaries of the track are influenced by this change in width of the track, with the result that the inwardly directed peaks of the boundaries may overlap and lose their clean sine shape. This causes distortion in the reproduction from such track.

Such width variations are particularly harmful in the methods of mechanical recording in which the distance between the central position of the cutter and the surface of thecarrier is stepwise or continuously altered in accordance with the amplitudes of the vibrations being recorded for the purpose of lessening the load on the cutting tool.

While a nonuniformity in the.

A method of stepwise altering the central position of the cutting tool has been described in the copending U. 8. Patent application No. 11,371 to Six et al, filed March 15, 1935. In such a method the transparent portion of the track is reduced as much as possible and the inwardlydirected peaks of the boundaries of the track are very close to each other, so that even minute changes. in the neutral position of the cutter relative to the surface of the carrier due to variation in film thickness might result in damage or mutilation of the track.

Several methods have been proposed to overcome the diificulties due to varying thickness in mechanical recording. When recording with a cutting tool which is vibrated in the direction of the plane of the carrier, it has been proposed to employ a feeler, which is either mechanically connected tothe suspension means of the cutting tool .to maintain constant the central position of the cutting tool with regard to the carrier Burface, or which feeler is arranged stationary, whereas the carrier support is adjustable under the influence of a weight in accordance with the varying thickness of the carrier.

Such feeler arrangements are, however, unsuited for a cutter which is vibrated perpendicularly to the surface of the carrier. as in this case the cutting surface of the carrier must remain stationary in respect to the central po- 0 sition of the cutter; i. e., movement of the cutter should not alter the position of the carrier. Further, in such re-recording the cutter exerts a high pressure (of about 1 kg.) upon the carrier, and feelers with mechanical gear would be unsuited. Also in this method the requirements as to the accurate compensation of the carrier thickness is much more exacting than in 'other methods of recording.

In mechanical recording with a rotary cutting or grinding disc upon a film which is curved at the point of recording, it has been proposed to arrange a curved support adjacent to the recording point. Thereby the film was to be arranged: with its cutting surface against the support and 5 was pressed by a pivoted, curved pressing member. However, due to the pivoting of the pressing member, and also to the curvature of the bearing surfaces of both the support and the pressing member, a uniform engagement of the 5 film was impossible for diiferent thicknesses of the film.

' In accordance with the present invention, the disadvantages due to the varying thickness of the carrier are eliminated by providing at the 5K point of recording a support having a plane surface and an aperture for the cutting tool, the support being interposed between the carrier and the recording device, and whereby the cutting surface of thecarrier lies against said plane surface. On the other side of the carrier is located a pressing member having a plane surface preferably of an unyielding material such as wood and pressing against the carrier at a pressure which is higher than that produced on the carrier by the cutting tool, and being adapted to move as a unit substantially normally to the supporting surface.

To minimize the friction between the carrier and the surfaces, and thus to avoid partial longitudinal oscillations of the carrier while it passes the recording point, I preferably provide proper lubrication.

Furthermore, to prevent undesired longitudinal vibrations of the film the pressing member is preferably so arranged as to be free from oscillation in this direction.

Preferably damping means are also provided to prevent the perpendicular movement of the pressing member from becoming a periodic movement which would set the recording member into vibration. For example, if the pressing member is spring-biased against the film, additional damping means are preferably provided, and also if pressure by weight is used-either directly or indirectly, for example by means of a lever gear-suitable damping means will also improve the operation.

I prefer to combine the pressing means and the damping means by using a rubber sheet with a micrometer screw; the rubber sheet serving both as a spring and as a damping means, and the screw serving for adjustment.

In order that my invention will be more clearly understood and readily carried into effect, it will be more fully explained with reference to the accompanying drawing, in which:

Figure 1 is an enlarged front view, partly in section, of a cutting tool while cutting a vibration track into a carrier;

Fig. 2 is an enlarged plan view of the carrier shown in Fig. 1, having a vibration track cut therein;

Fig. 3 is a similar plan view of a carrier of nonuniform thickness with an unmodulated vibration track;

Fig. 4 is a similar plan view of a carrier having a vibration track produced by a cutting tool whose central position has been stepwise altered.

Fig. 5 is a diagrammatic view on an enlarged scale showing the effect of a curved support on the cutting angle of the cutting tool;

Fig. 6 is a perspective view of a device to compensate the thickness variation of the carrier according to the invention;

Fig. '7 is an end view of Fig. 6 with several parts removed and showing the carrier;

Fig. .8 is a perspective view of a pressing member'as shown in Fig. 7;

Fig. 9 is a perspective view of a supporting member as shown in Fig. 6;

'Fig. 10 is a modification of the support of Fig. 9 showing lubricating grooves.

Fig. 11 is a perspective View of a device similar to that of Fig. 6, but using a weight for obtaining the pressing force.

Referring to Fig. 1, a cutting tool 1 having a V-shaped cutting edge forming a large apical angle is vibrated in the direction of t e d u l headed arrow (perpendicularly to the carrier 30) in accordance with the vibrations to be recorded, and cuts a vibration track into the carrier which moves in a direction perpendicular to the plane of the drawing. The carrier 30 consists of three superimposed layers, namely, a base layer 2 of transparent material, for instance celluloid, a cutting layer 3 of transparent and easily cut material, for instance gelatin, and a very thin covering layer 4 of an opaque material, for example an exposed. photographic emulsion or an opaque dye.

As shown in Fig. 2, the vibration track so produced forms a transparent portion bordered by two complementary boundary lines, because of the corresponding removal of portions of the covering layer 3, and is surrounded by the remaining opaque portion indicated by the crosshatching.

When the cutting tool i is not vibrated, i. e., not'actuated by the recording means it cuts into the carrier an unmodulated track whichprovided the carrier thickness is uniform-has a constant width b and is bounded by the two straight dot-dash lines 6.

In practice, however", the thickness of the carrier, for example of films, is not uniform and the track produced by a stationary cutting tool, instead of being of constant width, varies due to the variation of thickness of the film. Such a track with a variable width b is shown in Fig. 3.

As has been stated above, such width variations of the unmodulated track may cause, during recording, an overlapping of the inwardlydirected peaks of the boundaries of the track and results in corresponding distortion in the reproduction. Such width variations of the unmodulated track are particularly harmful when, in mechanical recording, a method is used in which the central position of the cutting tool is varied continuously or stepwise in accordance with the amplitudes of the sound being recorded.

Fig. 4 shows a track produced in accordance with such a method as more fully described in the above-mentioned copending application Ser. No. 11,371, and in which the central position of the cutting tool is stepwise altered in accordance with the range of amplitudes of the vi- .film thickness and for maintaining the width of the unmodulated track of the cutter constant, is shown in Figs. 6 to 10.

The device shown in these figures consists of a channel-shaped support 8 having a plane bearing surface M, which is provided at the point of recording with a rectangular aperture 18 through which projects a cutting tool 37 secured to the holder 38 of a recording device 39 (see Fig. 7). A carrier l6, which may be a threelayer film as shown in Fig. 1, is passed in the direction of the arrow i! (Fig. 6) through the channel of support 8; the cutting surface of the film being in contact with the support surface 3i. Slidably fitting within the channel of support ii and bearing upon the carrier i6 is a pressing block 9 (see Fig. 8).

The surface with which the pressing block 5? bears against the carrier consists of a rectangular portion, and two narrow side portions 2l--2l; these three portions lying in the same plane. The portion 20 is slightly larger than the aperture Hi and covers the same when the pressing member t is in place. .The portions ii--fi serve to guide the film and the rectangular portion ill prevents perpendicular movement of the film at the point of recording.

The groove it formed at the side of the pressing surface it, and in which travel the guide perforations of the film, protects the perforated parts of the film from frictional contact with the surface of member t, and thereby prevents any shaving action of the film taking place at this point.

lit must be well understood, that the channelshaped support t (Fig. 9) may be also constructed, with the aperture it for instance in the middle. In this case,. the pressing block t is provided with two grooves if, one on each side of the pressing surface it, so as to obtain a suitable device for recording on a carrier provided with two rows of perforations and having a greater width, and to reduce the influence of the perforations on the soundtrack to be recorded.

The pressing block t has fixed to one end a short flexible strip ii, which is removably secured by means of two screws it to one leg of an angle it, whose other leg is fastened to the supporting member t by screws lit-it. Because of the flexibility of the strip ii the pressing block t can move in a direction perpendicular to the surface of the film and thus follow the irregularities in the thickness ofthe film. On the other hand, the shortness of the strip ill prevents movementof the block t in the direction' of the movement of the film.

Arranged on top of the pressing member 9 is A a pad or sheet it of resilient material, for instance of rubber; pressure being applied to the sheet it and through it to the block t, by means of a finely adjustable or micrometer screw it,

which acts on an interposed bearing plate it. The screw it cooperates with a suitably threaded support (not shown) which is stationary with respect to the support ii. The proper amount of pressure is obtained by manual adjustment of screw it.

Instead of using the method illustrated in Fig. 6, pressure on the member i may be obtained by the method illustrated in Fig. ll, The device shown in Fig. ii: is similar to that of Fig. 6 with the exception that the screw it is replaced by a weighted leverf lt pivotally supported at th and carrying on its free end a weight ti, whereby a constant" force is applied to the pressing member t.

The bearing plate ill is-recessedso as to bear upon the sheet it with its two end surfaces tt-tb only, and the pressing member is only loaded at its two ends, which prevents the occurrence of local changes in the pressure between the pressing member and the carrier.

The sheet of resilient material it serves also as a damping means, to prevent the pressing member from vibrating periodically in the direction normal to the surface of the carrier. Thus it will be noted that the cutting surface of the,

film which is in intimate contact with the bearing surface til always remains at the same-distance from the cutting tool, irrespective of any cause a lesser or greater compression of the resilient pad i9 without afiecting, however, the

depths and thus the widths of the unmodulated I track of the cutting tool. i v

To reduce the friction between the film and the bearing. surface it of the support and the surfaces iii-fl of the pressing member, it is preferable to provide lubricating means, For example, the film may be lubricated with grease or oil, or air lubrication may be provided. .In

,the latter case, the bearing surfaces iil-fll of the pressing member' and/or the surface ti of the supporting member are provided with grooves is extending in the direction of or normal to the direction of movement of the film. As indicated-in'l 'ig. 10, the surface of the support t is provided with longitudinal grooves it whereby a thin layer of air, which has a lubricating action, is enclosed between "the aim and the bearing surfaces. Particularly good results are obtainedby making the pressing member, instead of metal, o f'a material like wood, especially of wood which contains oil, for example, palm wood or pockwood; such materials inherently providing for lubricating action in which case separate lubricatin means are rendered unnecessary.

In addition to the advantages of producing an faces independently of the film thickness, the plane bearing surface of the support has the further advantage that the proper cutting angle of the cutting tool is always insured. Changes in the cutting angle may be caused by the fact that the cutting tools are not always of the same thickness and when fixed in the holder this difierence in thickness may cause a change in the cutting angle. This appears from Pg. 5 in which a cutting tool 33 is shown while cutting a track in a' film moving in the direction ofthe arrow over a curved supportdt. The tool til forms, at the recording point, a cutting angle a with the tangent to the film. If a cutting tool it of slightly greater thickness is used a larger cutting angle a will result, whereas if a slightly thinner cutting tool it" is used a smaller cutting angle 0." results. With the use of a plane support such variations of the cutting angle are avoided and no special measures for correcting this angle are necessary.

Care should be taken that the specific pressure upon the surface of the carrier remains below a maximum value, the exact value of which depends upon the particular carrier used. This has been found to be very important as in methods employing a recording member vibrat ing normally to the carrier surface pressures of considerable values may occur. When the speciflc pressure becomes too large, the carrier, particularly if a soft gelatin cutting layer is used, becomes damaged and the record is unserviceable.

When using carriers having a gelatin cutting layer, I have found that a surface pressure of about 1 kg. per sq. cm. may be used without injurious results. Of course the admissible pressure will vary for different typesof carriers and cutting layers and this value may be higher or lower than the given value. A plane support has also the advantage that the exact requirements can be readily determined and complied with, as it is possible to exactly determine the value of the surface pressure.

While I have described my invention in connection with specific examples and in specific applications, I do not wish to be limited thereto, but desire the appended claims to be construed as broadly as permissible in view of the prior art.

What I claim is:

1. A device for usein mechanically recording vibrations on a carrier by means of a recording member vibrated substantially perpendicularly to the surface of the carrier to produce an optically-reproducible vibration track whose width variations are an enlargement of the amplitudes of the recording member, comprising a supporting member disposed at the recording point and having a plane bearing surface in contact with the cutting surface of the carrier, and a pressing member having a plane pressing surface'bearing upon the carrier, said pressing member being adapted to move as a unit substantially normally to the said bearing surface and to press the carrier against said bearing surface. 7

2. A device for use in mechanically recording vibrations on a carrier by means of a recording member vibrated substantially perpendicularly to the surface of the carrier to produce an optically-reproducible vibration track whose width variations are an enlargement of the amplitudes of the recording member, comprising a supporting member disposed at the recording point and having a plane bearing surface in contact with the cutting surface of the carrier, and a pressing member having a plane pressing surface of unyielding material bearing on the carrier, said pressing member being adapted to move as a unit substantially perpendicularly to said bearing surface and to press the carrier against said bearing surface with a specific pressure which is greater than the pressure exerted on the carrier by the recording member and less than the maximum permissible pressure which the carrier can stand without injury.

3. A device for use in mechanically recording vibrations on a carrier by means of a recording member vibrated substantially perpendicularly to the surface of the carrier to produce an optically-reproducible vibration track whose width variations are an enlargement of the amplitudes of the recording member, comprising a supporting member disposed at the recording point and having a plane bearing surface in contact with the cutting surface of the carrier, a pressing member having a plane pressing surface of unc yielding material bearing upon the carrier to press same against said bearing surface, said pressing member being adapted to move as a unit substantially normally to said bearing surface, and means to lubricate said carrier: said means being disposed before the recording point in the direction of the carrier.

4. A device for use in mechanically recording vibrations on a carrier by means of a recording member vibrated substantially perpendicularly to,the surface of the carrier to produce a vibration trackwhose width variations are an enlargement of the amplitudes of the recording member, comprising a supporting member disposed at the recording point and having a plane bearing surface in contact with the cutting surface of the carrier, a pressing member having a plane pressing surface of "unyielding material bearing upon the carrier to press same against said bearing surface, said pressing member being adapted to move as a unit substantially perpendicularly to said bearing surface, and means to prevent'said pressing member from moving in the direction of movement of the carrier.

5. A device for use in mechanically recording vibrations on a carrier by means of a recording member vibrated substantially perpendicularly to the surface of the carrier to produce an optically-reproducible vibration track whose width variations are an enlargement of the amplitudes of the recording member, comprising a supporting member disposed at the recording point and having a plane bearing surface in contact with the cutting surface of the carrier, a pressing member having a plane pressing surface of unyielding material bearing on said carrier to press same against said bearing surface, said pressing member being adapted to move as a unit only in a direction substantially normally to said bearing surface, and means to prevent periodic movement of said pressing member.

6. A device for use in mechanically recording vibrations on a carrier by means of a recording member vibrated substantially perpendicularly to the surface of the carrier to produce an optically-reproducible vibration track whose width variations are an enlargement of the amplitudes of the recording member, comprising a supporting member disposed at the recording point and having a plane bearing surface in contact with the cutting surface of the carrier, a pressing member adapted to move as a unit in a direction substantially normal to the 'said bearing surface and having a plane pressing surface of unyielding material in contact with the carrier, a spring acting on said pressing member to press said carrier against said bearing surface, and damping means to prevent a periodic movement of said pressing member.

7. A device for use in mechanically recording vibrations on a carrier by means of a recording member vibrated substantially perpendicularly to the surface of the carrier, comprising a supporting member disposed at the recording point and having a plane bearing surface in contact with the cutting surface of the carrier, a pressing member adapted to move as a unit substantially perpendicularly and having a plane pressing surface of metal in contact with the carrier, and means to press said pressing member against said carrier.

8. A device for use in mechanically recording vibrations ona carrier by means of a recording member vibrated substantially perpendicularly to the surface of the carrier, comprising a supporting member disposed at the recording point and having a plane bearing surface in contact with thecutting surface of the arrier, a pressing member having a plane pressing surface bearing upon the carrier, a rubber pad bearing on said pressing member, a plate bearing upon said pad, and means acting upon-said plate to adjust the stress in said pad.

9. A device for use in mechanically recording vibrations on a carrier by means of a recording member vibrated substantially perpendicularly to the surface'of the carrier, comprising a supporting member disposed at the recording point and having a plane bearing surface in contact with the cutting surface of the carrier, a pressing member having a plane pressing surface bearing upon said carrier, and a weight acting on said pressing member to press the carrier against said bearing surface.

10. A device for use in mechanically record ing vibrations on a carrier by means of a recording member vibrated substantially perpendicularly to the surface of the carrier, comprising a supporting member disposed at the recording point and having a plane bearing surface in contact with the cutting surface of the carrier, a pressing member having a plane pressing surface bearing upon said carrier, a weight acting on said pressing member to press the carrier against said bearing surface, ,and means to dampen the movement of said pressing member.

11. A device for use in mechanically recording vibrations on a carrier by means of a recording member vibrated substantially perpendicularly to the surface of the carrier, comprising a supporting member disposed at the recording point and having a plane bearing surface in contact with the cutting surface of the carrier, a pressing member having a plane pressing surface bearing upon the carrier 'to'press same against the bearing surface, said pressing member being adapted to move relatively to said supporting member, at least one of said surfaces being grooved in the longitudinal direction of the carit rier.

12. A device for use in mechanically recording vibrations on a carrier by means of avrecording member vibrated substantially perpendicularly to the surface of the carrier, comprising a supporting member disposed at the recording point and having a plane bearing surface in contact with the cutting surface of the carrier, a pressing member having a plane pressing surface bearing upon the carrier to press same against said bearing surface, said pressing member being "adapted to move relatively to said supporting member, at least one of said surfaces being grooved perpendicularly to the longitudinal direction of the carrier.

cording member vibrated substantially perpendicularly to the surface of the carrier, comprising a supporting member disposed at the recording point and having a plane bearing surface in contact with the cutting surface of the carrier, and a pressing member adapted to move relatively to said supporting member and having a plane pressing surface bearing upon the carrier to press same against said bearing surface, at least one of said members being of wood.

14. A device for use in mechanically recordin vibrations on a carrier by means of a recording member vibrated substantially perpendicularly to the surface of the carrier, comprising a supporting member disposed at the recording point and having a plane bearing surface in contact with the cutting surface of the carrier, and a pressing member adapted to move relatively to said supporting member and having a plane pressing surface bearing upon the carrier to press same against said bearing surface, at least one of said members being of pockwood.

15. A device for use in mechanically recording vibrations on a carrier by means of a recording member vibrated substantially perpendicularly to the surface of the carrier, comprising a supporting member disposed at the recording point and having a plane bearing surface in contact with the cutting surface of the carrier, and a pressing member having a pressing surface comprising a central portion adjacent to the recording point and two'narrower edge portions, said portions lying in the same plane, said pressing'member being adapted to move relatively to said supporting member and to press the carrier against the bearing surface of said supporting member.

' WILLEM SIX. 

